If the second amendment is either a protection of the nation in lieu of a standing army, or a protection of the individual states from national overreach; it is moribund.
Thus the second amendment should be repealed.

We now have a standing army, many times more powerful than any possible foe. So the need for an armed citizenry to protect the nation in times of invasion no longer exists.

The states have their own standing armies in the form of the various national guards. Many of these national guards are more powerful than a majority of national armies. If a state had to protect itself from federal overreach it would depend on the national guard rather than the armed citizen/militia.
We have empirical evidence that armed citizens are not necessary for the overthrow of tyrannical government.
We also have evidence that in times of civil strife armed citizens are just as likely to use firearms in support of tyrannical governments as they are to use them against.

Any justification for the retention of the 2nd that depends on the relevance of a militia is at best archaic.

To take it one step further, the 2nd amendment should be repealed because of the danger it represents to individual liberty.
According to the militia acts, all citizens from 18 to middle age are members of the militia.
For a militia to be effective the members of that militia have to be registered and the number and types of weapons they have needs to be know.
There is nothing in the 2nd that bars registration and the militia clause would seem to make it mandatory.
During those times in which there was an active militia, the militia was called out for regular inspection and training. Under the 2nd amendment it would be well within both federal and state governments powers to call up the such a militia today.
A tyrannical or corrupt government could use this ability as a way of putting financial burdens on their opposition. They could use this ability to propagandize or coerce militia members into using force against their fellow citizens.

So if you want an argument against the 2nd amendment I think those will do for a start.